There is a case where a control system used in the field of FA is configured by a plurality of devices, with the devices being connected through a network. For example, programmable logic controllers (PLC) or programmable display devices (human machine interface (HMI)) are applicable as the devices that constitute the control system. In recent years, there has been a trend for control systems to become increasingly large. Such development of large control systems is done by multiple companies or teams. These companies or teams concurrently develop the respective development areas for which they are responsible. This makes it possible to develop control systems in short periods.
As a technique for dividing the control system into functions, Patent Literature 1, for example, has disclosed a technique for dividing a program into functions on a PLC-by-PLC basis and allocating a divided program to individual PLCs without taking the interface between the PLCs into account.